1. Field of the Invention
The present disclosure relates to touch technology, and in particular, relates to a touch panel.
2. Description of the Related Art
Recently, touch panel techniques have been developed to be a main input interface and have been popularly applied in various electronic products, such as mobile phones, personal digital assistants (PDA), and handheld personal computers. Touch-sensing elements of the touch panel are electrically connected to bonding pads through wires and the bonding pads are bonded with a flexible printed circuit board. Therefore, sensing-signals of the touch-sensing elements can be conveyed to an exterior processor for performing a treatment of the sensing-signals.
In general, the touch-sensing elements and the wires are electrically connected together by a front-to-rear connection (or a head-to-end connection) method. Therefore, a protection element is disposed directly on the touch-sensing elements and the wires to prevent the touch-sensing elements and wires from being affected by the environment or the other processes. However, the bonding pads and the flexible printed circuit board are electrically connected together by an upper-to-lower overlapping connection method. There is usually no protection element disposed on the bonding pads to avoid affecting the conductive behavior between the bonding pads and the flexible printed circuit board. The bonding pads are usually formed by stacking several layers of conductive elements, wherein a middle-layered conductive element is formed of a better conductive material, for example aluminum, to enhance the conductivity of the bonding pads. However, the materials of better conductivity usually provide poor protection against the environment or other processes. Therefore, conductive elements having a better protective function, for example molybdenum, are used as an upper-layered conductive element and a lower-layered conductive element to form the bonding pads. Although the upper surface and the lower surface of the middle-layered conductive element of the bonding pad are protected by the other conductive elements, the sidewalls of the middle-layered conductive element of the bonding pad are not protected by any protection element and may be affected by the environment, for example oxidation or other processes, through for example a process using an acid solution, a basic solution, or a cleaning liquid. As a result, the conductive quality between the bonding pads of the touch panel and the flexible printed circuit board is poor and the reliability of the touch panel is thereby reduced.